c-string

How to convert the time to a c string in c?

Hi, I wanna to write something to a .txt file in .c file, but required to name that file with the current timestamp as the postfix, just like filename_2010_08_19_20_30. So I have to define the filename char array first and process the filename by myself?Assign the character one by one? Is there any easy way to do that? ...